Wooden pallets are often used to transport cargo on aircraft. The cargo compartments of wide body passenger airplanes use a conveyor system in the belly with locks spaced at precise intervals. These locks hold cargo containers called LD3’s or aluminum pallets called cookie sheets. Air freight that is too large to fit in an LD3 container is often on wooden pallets strapped to a cookie sheet. Google LD3 and aircraft cookie sheet. It is very likely this aircraft had wooden pallets onboard.
Many thanks for the info!